Electronics Forum | Wed Nov 01 08:55:05 EST 2006 | russ
See if the solder is leaving the pad(s) and is wicking up the component. This is long shot but I have seen something similar to this possibly in a wave process. We had a very thin board and a very large QFP on top. During wave operation the solder
Electronics Forum | Thu Sep 26 14:45:36 EDT 2019 | dwl
Excellent X-ray picture, very helpful! It looks like you have a lot of voiding on the center thermal pad. My guess is that outgassing is pushing solder off the pad which is forming solder balls outside the body of the component package. The first
Industry News | 2018-08-16 19:58:50.0
The SMTA Capital Chapter is holding its upcoming Capital Expo and Tech Forum at Johns Hopkins University / Applied Physics Lab, Kossiakoff Center, 11100 Johns Hopkins Road, Laurel, MD 20723, on Thursday, August 23rd.
Industry News | 2013-11-14 18:21:25.0
Indium Corporation's Sze Pei Lim, Technical Manager - Asia-Pacific Operations, and Sehar Samiappan, Area Technical Manager, will present at the IPC Conference on Assembly and Reliability November 20 in Bangkok, Thailand.
Technical Library | 2018-09-26 20:33:26.0
Bottom terminated components, or BTCs, have been rapidly incorporated into PCB designs because of their low cost, small footprint and overall reliability. The combination of leadless terminations with underside ground/thermal pads have presented a multitude of challenges to PCB assemblers, including tilting, poor solder fillet formation, difficult inspection and – most notably – center pad voiding. Voids in large SMT solder joints can be difficult to predict and control due to the variety of input variables that can influence their formation. Solder paste chemistries, PCB final finishes, and reflow profiles and atmospheres have all been scrutinized, and their effects well documented. Additionally, many of the published center pad voiding studies have focused on optimizing center pad footprint and stencil aperture designs. This study focuses on I/O pad stencil modifications rather than center pad modifications. It shows a no-cost, easily implemented I/O design guideline that can be deployed to consistently and repeatedly reduce void formation on BTC-style packages.
SMTnet Express, September 27, 2018, Subscribers: 31,354, Companies: 11,055, Users: 25,237 Assessing the Effectiveness of I/O Stencil Aperture Modifications on BTC Void Reduction Carlos Tafoya, Gustavo Ramirez, Timothy O'Neill; AIM Solder Bottom
SMTnet Express, October 3, 2018, Subscribers: 31,373, Companies: 11,056, Users: 25,258 Fill the Void II: An Investigation into Methods of Reducing Voiding Tony Lentz - FCT Assembly , Patty Chonis, JB Byers - A-Tek Systems Voids in solder joints
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. X-ray inspection allows each pad to be seen clearly, as well as the large central soldering pad. Missing solder, open and bridged solder pads can easily be seen, and voiding can be measured on each pad, and in the central large pad where higher voiding can lead to poorer thermal efficiency
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